Motion Capture Overview

Inertial

These use an inertial sensor on each limb for measurement, as well as a software model of the biomechanics of the human body to help compensate for the innate drift that inertial systems experience.

Benefits: – Wide area tracking (can combine with an Intersense IS1200 to lock the character into the same tracking position as the Previzion camera tracking data). Can track over a whole soundstage. – Can operate under costumes; does not need to be visible

Problems: – Inertial tracking not as accurate as optical based methods – No provision for face or finger tracking – Problems can arise when character’s feet are off the ground

Active LED Marker

Manufacturers: – PhaseSpace

Uses pulsed LED lights blinking at specific frequencies, along with very fast linear array cameras arranged in a circle around the tracking volume

Benefits: – Most accurate tracking, in millimeter range – Each LED blinks at a different rate, so the markers can’t get mixed up — less need for data cleanup in post production – Provisions for face and finger tracking – Very, very fast tracking — up to 400 Hz

Problems: – Expensive to scale to large tracking ranges (needs many cameras) – Markers on subject need to be wired up and visible

Passive Marker Optical

Manufacturers: – Vicon – Motion Analysis – NaturalPoint

Uses passive retro-reflective “ping pong balls” on subject, with optical cameras arranged in a circle around the tracking volume.

Problems: – Markers have to be visible on subject – Cameras can be confused on which marker is which, leading to increased data cleanup in post production – Expensive to scale to large tracking ranges (need many cameras)